Assessment of physicochemical properties and fisheries activities in Koga Reservoir, head of Blue Nile River Basin, Ethiopia

Abstract

Reservoirs are potential freshwater bodies that have a significant impact on the development of Ethiopia's fishing industry. This study aimed to assess the potential yield of fish and the current status of fishing activities in Koga Reservoir. Fishermen’s cooperative management team members were selected purposefully to assess the reservoir fisheries activities. Four sampling sites were selected in the reservoir for in-situ measurements of physicochemical properties. Primary data was obtained through semi-structured questionnaires, and group discussion. Empirical models were employed to estimate the reservoir fisheries potential. One-way ANOVA and correlation were used for reservoir water quality data analysis. The result indicated that the analysis of physicochemical and nutrients showed non-significant differences among sampling sites except for TDS (P<0.005). The mean fisheries potential of the reservoir was estimated to 104.85 tons/year while capture fisheries has been declining due to overexploitation and over abstraction of the reservoir water. More than 60 fishermen benefited from the reservoir capture fisheries. According to the cage farm investor response, the productivity of cage culture was attractive in the reservoir, but it was not sustainable due to management and environmental limitations. This study indicated that the water quality of the reservoir was found within an acceptable range for fish and irrigation, however, depletion of dissolved oxygen and turbidity were critical problems in the reservoir cage culture farm. An urgent management action is needed to sustain the reservoir fisheries based on the capacity of the reservoirs’ potential by restricting the number of fishermen and fishing effort and focusing on stock enhancement.